Effect of the additives PVP and MTS on structural properties and synthesis mechanism of Beta zeolite

Beta zeolites were successfully synthesized via hydrothermal method using sodium aluminate as aluminium source, silica sol (Ludox) as silicon source and TEAOH as template, respectively. The effects of different additives polyvinyl pyrrolidone (PVP) and Methyltriethoxysilane (MTS) on their structural properties and synthesis mechanism were investigated in detail by various characterizations, such as XRD, TEM, BET, ICP, ²⁹Si-NMR and NH₃-TPD method. Also, their catalytic performances were evaluated through catalytic cracking of cumene. The results showed that the beta zeolite obtained in the PVP-added system presented a better crystallinity, higher Si/Al molar ratio (25.68), and larger surface area (772 m²/g). Comparably, the MTS-effected samples revealed a larger surface area (657 m²/g), higher Si/Al molar ratio (25.76), but lower crystallinity and smaller particle sizes (around 160-320 nm). Moreover, both of them exhibited a good catalytic activity for cumene cracking due to the existences of abundant and strong acid content.